Gastroesophageal reflux occurs when stomach fluid, which typically includes stomach acids, intermittently flows from the stomach into the esophagus. It is common for most people to experience this fluid reflux occasionally as heartburn. Gastroesophageal reflux disease (GERD) is a clinical condition in which the reflux of stomach fluid into the esophagus is frequent enough and severe enough to impact a patient's normal functioning or to cause damage to the esophagus.
In the lower part of the esophagus, where the esophagus meets the stomach, there is a muscular valve called the lower esophageal sphincter (LES). Normally, the LES relaxes to allow food to enter into the stomach from the esophagus. The LES then contracts to prevent stomach fluids from entering the esophagus. In GERD, the LES relaxes too frequently or at inappropriate times, allowing stomach fluids to reflux into the esophagus.
The most common symptom of GERD is heartburn. Acid reflux may also lead to esophageal inflammation, which causes symptoms such as painful swallowing and difficulty swallowing. Pulmonary symptoms such as coughing, wheezing, asthma, or inflammation of the vocal cords or throat may occur in some patients. More serious complications from GERD include esophageal ulcers and narrowing of the esophagus. The most serious complication from chronic GERD is a condition called Barrett's esophagus in which the epithelium of the esophagus is replaced with abnormal tissue. Barrett's esophagus is a risk factor for the development of cancer of the esophagus.
Accurate diagnosis of GERD is difficult but important. Accurate diagnosis allows identification of individuals at high risk for developing the complications associated with GERD. It is also important to be able to differentiate between gastroesophageal reflux, other gastrointestinal conditions, and various cardiac conditions. For example, the similarity between the symptoms of a heart attack and heartburn often lead to confusion about the cause of the symptoms.
Esophageal manometry, esophageal endoscopy, and esophageal pH monitoring are standard methods of measuring esophageal exposure to stomach acids and are currently used to diagnose GERD. A variety of endoscopic devices have been designed to monitor various parameters within the esophagus. Many devices require an indwelling catheter to maintain a sensor in place within the esophagus. The catheter protrudes from the patient's nasal or oral passage, however, causing discomfort and ordinarily requiring in-patient supervision.
The Bravo™ pH monitoring system, commercially available from Medtronic, Inc., of Minneapolis, Minn., is an example of a system useful in diagnosing esophageal reflux without the need for a catheter. The Bravo system includes an intra-luminal capsule that is temporarily placed within the esophagus via an endoscopic delivery device. The capsule has a vacuum cavity that captures a portion of the esophageal mucosal tissue. A physician then advances a pin through the captured tissue to secure the capsule relative to the esophageal wall. The capsule causes little discomfort and permits the patient to ambulate. Eventually, the capture tissue sloughs away and releases the capsule, which then passes through the patient's gastrointestinal tract for eventual discharge.
Table 1 below lists documents that disclose various techniques for diagnosing or detecting GERD, and other documents that disclose techniques for measuring conditions within the esophagus.
TABLE 1Pat. No.InventorsTitle5,833,625Essen-MollerAmbulatory Reflux Monitoring System5,967,986Cimochowski et al.Endoluminal Implant with Fluid Flow Sensing Capability6,285,897Kilcoyne et al.Remote Physiological Monitoring System6,689,056Kilcoyne et al.Implantable Monitoring ProbeUS20020103424Swoyer et al.Implantable medical device affixed internally within the gastrointestinal tract
All documents listed in Table 1 above are hereby incorporated by reference herein in their respective entireties. As those of ordinary skill in the art will appreciate readily upon reading the Summary of the Invention, Detailed Description of the Preferred Embodiments and Claims set forth below, many of the devices and methods disclosed in the patents of Table 1 may be modified advantageously by using the techniques of the present invention.